Maximum Adhesion Research Articles

Effect of a liquid bridge on the dynamic behavior of diamond wires during slicing

Diamond wire sawing with narrower kerf losses and thinner as-cut wafers is a critical technology to further reduce wafering costs in the semiconductor industry. Nevertheless, as the scale of the wire web decreases, the effect of the liquid bridge formed by the capillary condensation of the cutting fluid between the diamond wires becomes significant. Moreover, the transverse wire vibration reduces the wire web gap at certain moments, which makes it easier for the wires to adhere to each other after wetting, thus hindering the slicing process. Therefore, a dynamical model for a double-wire system with liquid bridge action was developed in this study based on the transverse vibration theory of a diamond wire under support excitations to reveal the action mechanism of the liquid bridge between diamond wires. The dynamic adhesion process between the diamond wires moving with the supports is discussed. The effects of the guide wheel manufacturing error and the sawing parameters on the critical gap for spontaneous adhesion between the diamond wires are analyzed. The results show that the static double-wire system does not generate spontaneous adhesion when the surface gap of the wires is between the critical gap for spontaneous adhesion and the maximum adhesion gap. The support excitation causes the transverse wire displacement, which increases the critical gap for spontaneous adhesion to increase the risk of wires adhesion. The critical gap for spontaneous adhesion increases with increases in the guide wheel manufacturing error and the wire span as well as the wire speed and decreases with increases in the wire groove diameter and the wire tension. When the manufacturing error is doubled, the critical gap for spontaneous adhesion will increase more than twice this error increment. Strict control of the guide wheel manufacturing error is the most effective way of reducing the risk of wires adhesion during processing. Increases in the guide wheel diameter and decreases in the wire span and the wire speed within a reasonable range, or enhancing the mechanical properties of the wire to improve its breaking force, also help to reduce the critical gap for spontaneous adhesion.

Influence of fibres and hardening accelerator on concrete for rigid pavements

This paper investigates the influence of hardening accelerator and steel fibre on concrete adhesion strength for the repair of rigid highway and airfield pavements. The concretes were mixed based on CEM II/A-S 42.5 and included MasterGlenium SKY 608 superplasticiser. Experiments with two variable concrete composition factors were carried out. The amount of steel fibre varied from 0 to 100 kg/m3 and the amount of SikaRapid hardening accelerator varied from 0 to 9.6 kg/m3. It was found that modified repair concretes have a sufficiently high adhesion strength to ‘old’ concrete, from 2.30 MPa when tested by the pull-off method and from 2.05 MPa when tested by the flexural strength test method. Fibre-reinforcement increases the adhesion strength of repaired concrete by 7–15% due to the reduction of shrinkage during hardening. Treating the contact surface of ‘old’ concrete with a primer additionally increases adhesion strength by 6–10%. The maximum adhesion strength of fibre-reinforced concrete to the base reaches 3 MPa. Due to the high early and design strength, modified steel fibre-reinforced concrete provides the possibility of quick resumption of traffic while ensuring the integrity of the road structure due to the joint work of the repair material with the old concrete repair area.

Bioinspired Adhesive Manufactured by Projection Microstereolithography 3D Printing Technology and Its Application

AbstractMany methods are used to manufacture bioinspired adhesive arrays such as photolithography and nanoimprinting methods, which are very high cost and time‐consuming. In this manuscript, projection microstereolithography 3D printing method is firstly adopted to prepare the bioinspired dry adhesive in several micrometers, which is low cost, time saving, convenient and can realize rapid, large‐scale, high‐precision, and controllable complex structure manufacture. The morphology and adhesive properties of four kinds of adhesive with flat punch, mushroom‐shaped, suction cup‐shaped, and titled micropillar structures are investigated. Scanning electron microscope (SEM) observation shows that the very regular pattern of the adhesive is generated and no collapse phenomenon is observed. The adhesion test results show the mushroom‐shaped adhesive reach the maximum adhesion of 15 KPa, which can be maintained after repeated uses. The contact angle of the adhesive is 143.7°, showing the good self‐cleaning ability. The mushroom‐shaped adhesive exhibits excellent adhesion property, high repeatability, and good self‐cleaning ability, which is further applied in grasping and transferring various surfaces such as solar panels, printed circuit board, flanges, and so on.

Experimental assessment of clayey layers for clogging potential in TBM tunnel driving and the influence of compositional factors

Clogging is common for tunnel boring machines, especially in clayey soil, and when it happens, the cutter heads or even the entire tunnelling device can become completely clogged, causing low excavation efficiency and high project costs. Because clogging stems from the adhesion of the excavated geomaterials, a better understanding of soil adhesion is required if clogging is to be avoided. Reported here are piston pull-out tests conducted to investigate the adhesion of natural clayey soils and artificial soils prepared using pure kaolin, montmorillonite, and silica sand, thereby enabling consideration of the effects of compositional factors (e.g., clay fraction, and mineralogy). The results show that with increasing water content, the adhesion stresses of the studied samples increased initially and then decreased. With increasing clay fraction, the adhesion stresses increased linearly because of the larger real contact area of the interface between the soil and a foreign object. With the addition of montmorillonite, the soil adhesion also increased significantly because of its microstructural properties. An updated semi-empirical diagram is proposed that allows the effects of compositional factors on clogging potential to be evaluated qualitatively. The measured maximum adhesion stresses of the studied samples occurred in the region of strong clogging in the semi-empirical diagram, showing the feasibility of using adhesion stress as an index for assessing the clogging of tunnel boring machines. This study provides valuable experimental data on soil adhesion and a better understanding of the adhesion behavior of clayey soils.

Measuring the Adhesion Force and the Spreading Radius between Droplets and a Solid Surface during Short-Time Spreading

When a droplet contacts a solid surface, the liquid spreads over the solid surface to minimize the total surface energy. This phenomenon is widespread in industrial production and nature, so research on droplet spreading is of great significance. Here, the adhesion force and the spreading radius during droplet spreading can be quantified using a highly sensitive photoelectric method. It is possible to study droplet spreading from two dimensions at the microscale. The adhesion force is measured by an optical lever, and the spreading radius is measured by an ultrafast electrical method. The measurement method allows the force resolution and the space-time resolution to reach the nanonewton lever and the nanosecond lever, respectively. We obtain the maximum spreading radius and the maximum adhesion force during short-time spreading through our technique. Moreover, we numerically simulate the droplet spreading process through the lattice Boltzmann solver and confirm the observed results. This study provides a new experimental technique for studying droplet spreading dynamics from multiple perspectives, which can deepen our understanding of droplet spreading and provide guidance for the development of new techniques.

Multifunctional Underwater Adhesive Film Enabled by a Single-Component Poly(ionic liquid).

Tremendous efforts have been devoted to exploiting synthetic wet adhesives for real-life applications. However, developing low-cost, robust, and multifunctional wet adhesive materials remains a considerable challenge. Herein, a wet adhesive composed of a single-component poly(ionic liquid) (PIL) that enables fast and robust underwater adhesion is reported. The PIL adhesive film possesses excellent stretchability and flexibility, enabling its anchoring on target substrates regardless of deformation and water scouring. Surface force measurements show the PIL can achieve a maximum adhesion of 56.7 mN·m-1 on diverse substrates (both hydrophilic and hydrophobic substrates) in aqueous media, within ∼30 s after being applied. The adhesion mechanisms of the PIL were revealed via the force measurements, and its robust wet adhesive capacity was ascribed to the synergy of different non-covalent interactions, such as of hydrogen bonding, cation-π, electrostatic, and van der Waals interactions. Surprisingly, this PIL adhesive film exhibited impressive underwater sound absorption capacity. The absorption coefficient of a 0.7 mm-thick PIL film to 4-30 kHz sound waves could be as high as 0.80-0.92. This work reports a multifunctional PIL wet adhesive that has promising applications in many areas and provides deep insights into interfacial interaction mechanisms underlying the wet adhesion capability of PILs.

Study on Adhesion Force of Graphene under Cylinder–Plane Contact

There are many cylinder–plane contacts in microaccelerators, microgyroscopes, and RF switches. Adhesion is one of the main factors affecting the manufacture and use of these micro–nano devices, but its research is insufficient. Graphene is expected to be used in these fields due to its excellent electrical and mechanical properties. Therefore, it is significant to research the adhesion force of graphene under cylinder–plane. Firstly, the meniscus formation process was introduced using the variable-water-contact-angle method. Secondly, the adhesion force of the graphene surface was measured with a cylindrical atomic-force-microscope probe. Finally, the contact area was considered as a number of nanoscale cylinders in contact with the plane, and the adhesion force of the cylinder–plane model was obtained. The results showed that there was a maximum adhesion force at a relative humidity of 65%. The adhesion force was evidently not time-dependent when the relative humidity was below 45%, because the meniscus cannot be formed on the graphene surface at low relative humidity. While the graphene contact surface formed a meniscus for higher relative humidity, and the adhesion force-versus-time curves first increased and then decreased to stability. Moreover, the relationship between adhesion force and substrate contact angle, roughness, relative humidity, and dwell time was established, and the number of cylinders was determined. The error between the modified theoretical model and the experimental values was only 6%.

Theoretical analysis of Si3N4/TiC interfacial properties and material preparation

Computer simulation plays an instrumental role in modern tool material design. In this study, we have calculated the temperature and pressure conditions for the phase transition of Si3N4 from α to β using first principles. The simulation results show that the phase transition temperature is 1330 K at a phase transition pressure of 32 MPa. The modulus of elasticity, hardness, ductile/brittle properties (B/G), Poisson's ratio, elastic anisotropy, and phonon spectral curves at the phase transition point were also calculated for the material at temperatures ranging from 873 K to 2073 K. According to the phase transition conditions, the surface energies of β-Si3N4 and TiC interfaces were calculated, and 4-layer models of Si3N4/TiC interfaces were constructed. The total energy and adhesion work of the Si3N4(110)/TiC(100) interface were analyzed by molecular dynamics. The results show that the Si3N4(110)/TiC(100) interface exhibits the maximum total energy and adhesion work of 12,806.62 eV and 2.33 J/m2, respectively, indicating that the interface bond was the most stable. Furthermore, the mechanical properties of different interface models were calculated and compared. The effects of Si3N4(110)/TiC(100) interfacial 5-layer and 6-layer crystalline surfaces and Si and Ti vacancy defects on the mechanical properties of the interfacial model were further investigated. The Si3N4/TiC composite ceramic tool material was prepared experimentally based on the results of simulation, and the properties show reasonable agreement.

Developing novel pothole patching mixtures utilizing iron ore waste as substitute to conventional aggregates with anti-stripping agent

Development of potholes on roads and streets of prominent cities in India after the onset of monsoons is a common phenomenon. The remedy used for restoration of potholes is termed as “Patching” which prevents rapid pavement deterioration and provides smooth traffic flow. The present article aims at developing novel pothole patching mixtures utilizing Iron Ore Waste (IOW) as substitute to conventional aggregates (CA) with anti-stripping agent (ASA). Mix design, adhesion, cohesion, and moisture sensitivity of pothole patching mixtures were evaluated. Mix design properties were evaluated adopting the Marshall method, adhesion properties were evaluated as per Virginia Department of Transportation (DOT) test procedure, cohesion properties were evaluated as per AASHTO TP-44–94, and moisture sensitivity was evaluated using modified Lottman test. The strength of the initial and fully cured stages improved when IOW was substituted with conventional aggregates, and it was higher than 5.1 kN. As for Cohesion, every substance under investigation retained more than 60% of its original composition at the initial test conditions (4 °C and five blows). When tested at 25 °C and five blows, cohesiveness exhibited the same pattern as when tested at 4 °C. The findings of the adhesive test showed that IOW-Z has a maximum adhesion time of 35 s. Moreover, IOW-based pothole patching mixtures outperformed CA-based pothole patching mixtures in terms of resistance to moisture sensitivity. Results also indicate addition of ASA improved adhesion, cohesion, and moisture sensitivity properties of pothole patching mixtures regardless of aggregate type.

Design of tough, strong and recyclable plant protein-based adhesive via dynamic covalent crosslinking chemistry

Conventional covalent crosslinked protein adhesives are brittle and cannot be reprocessed effectively, which restricts their practical application and limits the recyclability of wood-based panels. Inspired by biological cartilage and mussels, a tough, strong, and recyclable soybean protein isolate (SPI)-based adhesive, SPI/BP@mica, was designed in this study by co-assembly of mica and SPI via dynamic boron-nitrogen (B-N) coordinated catechol-derived boronic ester (B-O) interfacial bonding. The dynamic covalent B-O, imine, and hydrogen bonds significantly improve the cohesive strength and energy dissipation capacity of SPI/BP@mica adhesive for high mechanical strength and toughness. The maximum wet shear strength and adhesion of SPI/BP@mica adhesive bonded plywood reach 1.05 MPa and 518.8 MJ, respectively, at increases of 94.4 % and 601.2 % over the original SPI adhesive. More importantly, we achieved a breakthrough in the recyclability of protein-based wood adhesives. Due to the synergistic triple dynamic mechanism and B-N coordination depolymerization of B-O bonds, second-generation particleboard prepared by recycling via hot-pressing and solvent-assisted repolymerization showed a rupture modulus of 12.1 MPa; to this effect, we fabricated a next-generation sustainable, reusable adhesive. The SPI/BP@mica adhesive showed excellent mold resistance (50-day shelf life) and flame retardancy (LOI = 29.7 %). Further, the cost of SPI/BP@mica adhesive is equivalent to the price of the phenol formaldehyde resin adhesive commonly used for wood-based panel. The proposed design strategy may promote the functional modification of composites and provide workable guidance for constructing robust, recyclable protein-based materials.

Nanogel-Reinforced Polyacrylamide Hydrogel for Potential Vascular Adhesion

The adhesion and mechanical properties of hydrogels used for vascular wound repair often deteriorate dramatically on wet surfaces, resulting in ineffective repair. In this work, a poly(N-isopropyl acrylamide-co-dopamine methacrylamide) nanogel with dopamine groups was synthesized and introduced into a polyacrylamide (PAAm) hydrogel to produce temperature-responsive hydrogels, which greatly improved mechanical and adhesive properties of PAAm hydrogels. Nanogel-reinforced PAAm (NR-PAAm hydrogel) can adhere to the surface of various solid materials and biological tissues through special physical interactions, which exhibited different mechanical and adhesion properties as temperature changes below or above the lower critical solution temperature (LCST). The maximum adhesion of the NR-PAAm hydrogel on the aluminum surface was 78 kPa. In addition, the NR-PAAm hydrogel exhibited sufficient mechanical properties with a fracture stress of 103.6 kPa at a fracture strain of 1800%. The NR-PAAm hydrogel has good adhesion on wet surfaces and could adhere for 600 s at a pressure difference of 30 mmHg. Hence, the obtained temperature-responsive hydrogels have excellent tunable mechanical properties and adhesion properties, which provides a theoretical basis for the development of vascular repair materials in the future.

Geometric optimization of pillars for enhanced adhesion

Interfaces with enhanced dry adhesion have applications in various fields, including robotic grasping and microtransfer printing. Arrays of pillars or fibers with mushroom-like geometries and variations on these have been used to achieve relatively strong adhesion to a broad range of surfaces via surface forces. Here, we investigate the optimal geometries for adhesive pillars through a gradient-based optimization scheme. The scheme minimizes an objective function based on the strain energy release rate of a crack at the pillar edge. The optimal design yields a stress distribution at the interface that is nearly-uniform and free from edge stress singularities. Experiments were performed on millimeter-scale pillars to evaluate the efficacy of the designs. A maximum adhesion enhancement of 2x was achieved for a pillar with a stalk radius equal to half of the contact radius. The location of crack initiation was shifted to the center of the pillar from the edge, indicating that the optimal design does indeed significantly reduce the stress concentration in the near-edge region. This geometric optimization scheme is versatile and can be extended to other scenarios where the control of stresses through geometry can be used to improve the performance of adhered interfaces and bonded joints.

Exploiting dynamic thiourethane covalent bonds for enhanced adhesion of UV-curable metal coatings

UV-cured coatings with environmental-friendly trait are widely used in various industries. However, high internal stress during photopolymerization leads to low adhesion of coating, which limits its application on metal surface. In this work, polythiourethane-urethane acrylates (PTUA) with dynamic thiourethane bonds were designed and prepared via click reaction of 3,6-dioxa-1,8-octanedithiol (EDDT) and isophorone diisocyanate (IPDI), following by the reaction between 2-hydroxyethyl acrylate (HEA) and IPDI. By adjusting the IPDI/EDDT/HEA ratios, a series of PTUA with different molecular weights were synthesized. The structure of PTUA was characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR) and gel permeation chromatography (GPC). The incorporation of dynamic thiourethane bonds in UV-cured PTUA coating could release shrinkage stress via dissociative exchange of thiourethane bonds upon heating. After heating, the adhesion strength of the resulting coatings could be significantly improved. The maximum adhesion strength of the PTUA coating could reach 4.90 MPa, which was 2.5-fold increase compared with the coating without heating. This study demonstrated that adaptable thiourethane network was a promising candidate for UV-cured metal coating with enhanced adhesive performance.

Proximate chemical, functional, and texture characterization of papaya seed flour (Carica papaya) for the preparation of bread

Papaya seeds have important nutritional value and suitable functional properties for use in elaborating bakery products. The objective of this study was to determine the influence of substituting Carica papaya seeds flour for wheat flour in the preparation of white bread. Chemical composition, functional properties, and color were determined in flour. Dough’s textural tests (Uniaxial and biaxial extensibility, texture profile analysis -TPA-, adhesiveness) were conducted. TPA and color were measured on white bread. The results indicate that the maximum hardness, firmness, adhesiveness, cohesiveness, tenacity, and elasticity, as well as color quality, were affected by the presence of papaya seed flour (HSPa) in dough and bread. A decrease in the values of several functional properties, such as bulk density and foam formation capacity, of the samples containing HSPa that underwent different treatments, was observed compared to the control treatment (HT: 100 % wheat flour). The percentage of protein in the HSPa had a value of 21.61 % and for the HT of 12.27 %, while that of the ether extract was 22.22 % and 1.07 %. Regarding crude fiber, the values were 24.46 % and 0.061 % respectively; while the values for ash were 9.18 % and 0.27 %, respectively.

New insight into the role of the emulsified diesel droplet size in low rank coal flotation

Low-rank coal (LRC) is difficult to float using oily collectors due to poor floatability resulted from its abundant oxygen-containing groups. In recent years, numbers of emulsified collectors have been used to enhance LRC flotation. In this study, diesel-Span80 mixed collectors were added to high shear disperser producing emulsified diesel (ED) with a droplet size ranging from 12.51 to 4.58 µm to discuss the effects of droplets size on LRC flotation. The adsorption and spreading of ED on coal particle surfaces was evaluated by total organic carbon analyzer (TOC) and fourier-transform infrared spectroscopy (FTIR). The interaction between the oil droplets and coal particles was conducted using adhesion force measurement system. The flotation results indicated clean product obtained by using ED as the collector had the higher combustible recovery and lower ash content than conventional diesel (CD). It was interesting to find an optimal droplet size (7.68 μm) at which the ED flotation performance was maximized and beyond which the flotation performance deteriorated. The FTIR, adsorption amount and adhesion force results were all well consistent with the flotation results. The effect of ED droplet size on LRC flotation is controlled by ED dispersibility and concentration of adsorbed surfactant molecules on each ED droplet surface, playing a critical role in determining the optimal droplet size which delivers the largest hydrophobicity, maximum adsorption amount, highest maximum adhesion force and hence the best flotation performance.

INTERFACIAL BOND STRENGTH BETWEEN MICRO-SYNTHETIC FIBER-REINFORCED PATCH REPAIR MORTAR AND CONCRETE SUBSTRATE BASED ON PUSH-OFF TEST

A micro synthetic fiber-reinforced mortar has been developed as a patch repair material. The bond strength of this material is a crucial parameter for successful repair applications. The state of stress occurring at the interfacial plane between the repair material and the concrete substrate influences the bond strength requirements of patch repair material. Therefore, bond strength envelope criteria should be established using, among others, the interfacial adhesion and friction coefficient parameters. This research aims to determine the composite’s interfacial bond strength parameters (adhesion and friction coefficient) between micro-synthetic fiber-reinforced patch repair mortar (MSFRPRM) and concrete substrate by push-off tests. At this stage, the smooth joint texture limits the investigation. The fiber volume fraction and age of repair are considered. The tests were conducted at the age of 1, 3, 7, and 28 days. In addition to the laboratory experiment, this research used ATENA Science GiD to numerically simulate the push-off test and study the influence of the fiber volume on the adhesion and friction coefficient. The results show that at a fiber volume of 0.06%, the adhesion and friction coefficients increase from 1.15 to 2.33 MPa and 0.74 to 0.85, respectively, corresponding to age. Numerical simulation indicates that the maximum adhesion and friction coefficient occurs at the fiber volume fraction of 0.06%. Thus, the overall simulation results can be used in the future as a parameter to establish MSFRPRM and concrete substrate bond strength envelopes that will be useful for evaluating the suitability of MSFRPRM as repair materials under various states of stress. Keywords: Bond Strength, Concrete Patch Repair, Concrete Substrate, Micro-Synthetic Fiber-Reinforced Repair Mortar, Push-Off Test DOI： https://doi.org/10.35741/issn.0258-2724.58.1.20

Microstructure and mechanical properties of nanomultilayered AlTiN/Cu coatings prepared by a hybrid system of AIP and PDCMS

Due to its excellent lubricity and immiscibility with nitride phase, Cu has been added to nitrides to form a typical nanomultilayer structure. In this work, a hybrid deposition of AIP and PDCMS was applied to synthesize the multilayered AlTiN/Cu coatings, and the relationship between microstructure and mechanical properties was explored. The Cu-free AlTiN coating exhibited a c-TiAlN phase with a strong (200) preferred orientation. After adding Cu layer, the microstructure changed from a dense columnar structure into a featureless structure and then a fine-grained structure. As the Cu layer thickness reached 5.1 nm, the AlTiN/Cu(18.4 at.%) coating showed a double-phase of c-TiAlN and c-Cu. The thickness modulation period of Cu/AlTiN sublayer exhibited an excellent linear relationship with the content ratio of Cu/(Al + Ti). After adding Cu, the ion bombardment effect was weakened, the AlTiN/Cu(2.9 at.%) coating exhibited the lowest surface roughness of 18.9 nm, and the hardness gradually decreased from 34.6 to 13.2 GPa, accompanied by a relaxation of residual stress. Due to a high H/E * ratio, a maximum adhesion strength of 83.0 N was obtained at 2.9 at.% Cu.

Порівняльний аналіз ефективності сучасних методів активації іригантів у протоколі хемо-механічної обробки системи кореневого каналу (огляд літератури)

Resume. Development of apical periodontitis is the most common complication of unsuccessful endodontic treatment. Cleaning the root canal system is a crucial stage and the main factor for a successful endodontic protocol. Inability to remove debris from inaccessible branches of the root canal system, especially from the apical region, leads to and increases the risk of secondary infection. Selection of the optimal method for activating irrigants remains a current issue. According to the results of several studies, none of the individual irrigation activation techniques allows achieving ideal cleanliness in the root canal, but the use of laser, sonic, multisonic, and ultrasonic activation significantly improves the quality of cleaning and provides a prolonged antimicrobial effect by enhancing the diffusion of intracanal antiseptics, their hydrolytic and antibacterial effectiveness, which will eventually ensure maximum adhesion of filling materials. This, in turn, indicates the absence of a unified protocol that would provide stable irrigation efficiency and long-term results in endodontic treatment. The use of a protocol with combined activation of irrigants remains an open question among clinicians and scientists. Key words: endodontics, root canal, irrigation, activation, Sodium hypochlorite, smear layer, debris, ultrasonic, sonic activation, laser, Gentlewave, SAF (Self-Adjusting File), XP-Endo Finisher.

The need for instrumental measurement of the traction force of the friction drive of the vertical spindles of the cotton harvesting machine

An adhesion force measurement device was developed to measure the adhesion force of a friction drive in field conditions. The device consists of a lever with a pin, a dynamometer, and a hook. To measure the adhesion force, the car is stopped on a level area and the cleaning device is raised into the transport position. The movable section of the device is opened up to 30°. The selected spindle is brought closest to the opposite drum manually. The beginning of the serrated tape is inserted into the slot of the spindle rod and bent along the screw shell. A small gap is formed between the surface of the spindle rod and the bent section of the tape, allowing for insertion of the lever pin. When force is applied to turn the lever, it will either form a rigid connection with the spindle or slip along the surface of the belts, depending on whether or not maximum adhesion force has been reached. The dynamometer measures and displays the adhesion force on a certain scale. By knowing the lever arm from the stop to the pull cord and measuring angle between them, calculations can be made to determine adhesion force.

A 24-hour <i>Сandida sp.</i> biofilm formation dynamically assesed with modified macrometric method

The aim of the study was to study the dynamics of 24-hour Candida spp. biofilm formation by using a modified macrometric method. The proposed macrometric method solves the problem of accelerating and simplifying the quantitative assessment of the biofilm formation process, increases sensitivity due to allowing to avoid mistakes related to applied polystyrene material. The ease of implementing such a technique makes it accessible to any laboratory. Reference strains from the American Type Culture Collection (ATCC) and clinical isolates of Candida spp. isolated from the female reproductive tract with candida dysbiosis were used for the study. Biofilm formation of Candida spp. studied according to the OToole G.A. et al. method modified by us. The biological activity of Сandida sp. biofilm formation was monitored for 48 hours with 4-hour intervals, in winter season, the IV phase of the moon. A 48-hour fungal culture corresponding to relevant maximum adhesion on glass surface was used. The study chrono-design implied obtaining 6 diurnal measurements for the function evaluated with a 35-repetits of the experimental conditions. Amplitude-phase characteristics of the studied biorhythms were graphically represented using cosinor analysis serving as the basic method to identify and model cyclic processes in biological systems. The study proved that the ability of micromycete cells to adhere is significantly higher in the stationary vs. logarithmic growth phase (p 0.05). The chronobiological technique used here allowed to reveal the presence of diurnal fungal film-forming activity (p 0.05) and reveal the general patterns of manifestated properties in representatives of all candida species examined. It has been experimentally established that the sequence and consistency of the biological properties of clinical Сandida sp. isolates over time were not fundamentally dependent on the type of fungus. During the study, rhythmometric markers of the strain-related pathogenicity was established reflecting contribution of rhythm and the amplitude-phase characteristic. It has been proven that the activity of biofilm formation increases along the reference strains clinical isolates axis. For С. albicans the MannWhitney test data was 29, for C. tropicalis 26, and for C. krusei 30 (p 0.05). We believe that chronobiological method opens up new perspectives in the studying physiology of Candida spp. because it allows to dynamically predict state of microorganism and take into account features of urgent and long-term adaptation to various environmental factors. Identifying diurnal rhythms in biofilm-forming activity of various Сandida sp. strains opens up an opportunity to control viability of bacterial-fungal associations and predict related resistance to diverse antimicrobial agents.